Black Jupiter 2000 Function generator circuit.

[Yorkie]

I hadn't spotted that you do in fact have waveforms at the 527, as Mark has pointed out, (referring to post No 16), which is really good news, because as Mark says, that indicates that the complex part of the generator is working, and narrows it down to the output amp circuitry. It suggests that one or another of transistors TR13 - TR 21 are the culprits. You might like to roam around those transistors with the scope, but then if the transistors are easy to get to, you would probably spend less time changing them than you would trying to chase the fault all over the PCB.

Just a note of caution if the PCB has plated through holes: It's much safer and stands less risk of damage if you first clip the transistors off leaving the leads in the holes, then one by one, melt the solder on the leads and pull the leads gently out with tweezers or forceps. The same would apply to ICs - never try to desolder every pin with a desolder pump with the IC in place. First clip off all the IC pins with snips, leaving the pins in place on the PCB, then unsolder each pin and gently pull it out with tweezers. If you leave the IC or transistor in position and try to desolder the leads, they act as heat sinks and you risk overheating and damaging the PCB. In the case of plated through holes, you risk pulling out the sleeve due to the solder melting on the underside of the PCB, but not on the upper side.

Hope that helps a bit.